The Telegraph
Since 1st March, 1999
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Casual date caution: Mate can turn male-eater

Washington, Oct. 28 (Reuters): Casual dating can be dangerous.

A study of spiders shows female wolf spiders will eat strange-looking males that try to mate with them, but spare and even hook up with familiar-looking males.

The findings provide not just an interesting insight into spider behaviour, but may help explain actions by “higher” animals, said arachnologist Eileen Hebets of Cornell University in New York. “The female is using earlier experience that is going to affect her mate choice later,” Hebets said in a telephone interview. “It is reasonable to expect that is a common thing in other animals.”

Hebets worked with Schizocosa uetzi spiders, commonly known as wolf spiders.

They have an elaborate courtship ritual in which males arch their brown or black forelegs and vibrate their bodies.

The female, which is slightly larger, can choose to mate, to run away or to eat her suitor. Sometimes she eats the hapless male after mating, Hebets said.

Hebets painted the legs of male spiders either brown or black with nail polish, and then raised females with either brown- or black-marked males, but not both.

When the females became sexually mature, she would put into their boxes a male of either colour and watch what happened. The females were not exposed to males they already knew — just males marked with the same shade of nail polish.

“They just look like somebody they might know. None saw the same male ever,” Hebets said.

Writing in the Proceedings of the National Academy of Sciences, Hebets said the females were more likely to eat males painted with the “wrong” colour instead of mating with him. The more a female had been exposed to males with their legs painted a certain colour, the more likely she was to eat a male painted with the other colour, Hebets found.

“Finding this behaviour is really surprising. Social experience influences mate choice,” she said.

“It opens all kinds of possibilities. It could be this is a way of learning your species and making sure that when you get older, you are mating with the right species.”

She said it was the first study to look at social recognition in mate choice in an invertebrate.

“This shows that invertebrates have social recognition, and it can be maintained and remembered even through the molting process. These influences affect adult behaviour and possibly the evolution of traits,” she said.

Animals share many genes and humans share genes, and perhaps behaviours, with worms, flies and other bugs.

The colour of a male’s legs had no effects on whether a female decided to eat him after mating, Hebets said. But she said it was more unusual for a female wolf spider to eat a male she had just mated with.

“The percentage of post-copulatory cannibalisms were certainly nothing out of the ordinary,” she said.

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